Prismatic zincair battery for use with biological stimulator

ABSTRACT

The invention is a method for increasing the airflow to a Zinc-air battery such that the energy density is 500 mwh/cc to 1000 mwh/cc. This allows 8 to 16 hours use as a primary (throw-away) battery, with, for example, high-duty cycle, high-drain cochlear implants, and neuromuscular stimulators for nerves, muscles, and both nerves and muscles together. The systems incorporating the high energy density source are also part of the invention, as well as the resulting apparatus of the method. The uses of this inexpensive, i.e., a $1.00 per day, throw-away primary battery are new uses of the modified zinc-air battery and are directed toward helping people hear again, walk again, and regain body functionality which they have otherwise lost permanently.

FIELD OF THE INVENTION

[0001] The invention relates to the fields of portable high-density energy sources and small batteries capable of high power rates. It also relates to cochlear implant systems and to functional electric stimulation (FES), electric stimulators and to muscle and nerve stimulators (neuromuscular stimulators).

BACKGROUND OF THE INVENTION

[0002] Certain types of biological tissue stimulators, such as heart pacemakers, have a low duty cycle, and draw relatively little power over the course of some time frame, say, an hour. On the other hand, other biological stimulator types have a higher duty cycle, and may thus draw relatively higher power. Such higher power stimulators include, for example, a class of cochlear implants, as well as electrical stimulators for muscles and for nerves, such as in the case of stimulators for muscles which have their nerves inoperative because of trauma or degenerative illnesses, or, for nerves which may not be receiving normal synaptic input from the other ordinarily incoming other nerves, because of loss or disconnection (i.e., severing of those other nerves). For example, the spinal column nerves may be severed at some point, and the restoration of function below the cut area may be enabled with high-powered electric stimulators. These functions may include lower gastrointestinal (GI) function, urinary functions, sexual functions, and walking and limb movement functions, all of which may be served by functional electrical stimulators (FES) or other neuromuscular stimulators.

[0003] Today's primary battery sources tend to be of not high enough energy density, or if high enough energy density, too expensive and too large for any real use as a primary battery for any of the uses and systems above. Consequently, there is a real, unmet need for such systems, and such a power unit. A high amount of energy stored in a small space is a high energy density apparatus. Such an apparatus can potentially supply a high amount of energy per unit time (power) before it is exhausted. The current teaching of the art is away from this high energy density, relatively cheap, primary battery and systems which utilize it, and toward small, relatively low energy density, rechargeable batteries.

SUMMARY OF THE INVENTION

[0004] The present invention addresses the above and other needs by providing a primary battery for use in the systems above that is prismatic in shape, small in size, and inexpensive to make.

[0005] In accordance with one aspect, the invention provides a method for increasing the airflow to a zinc-air battery such that the energy density is 500 mwh/cc to 1000 mwh/cc. This thereby allows the battery to be used for approximately 8 to 16 hours as a primary (throwaway) battery, with, for example, high-duty cycle, high-drain cochlear implants, and neuromuscular stimulators for nerves, muscles, and for nerves and muscles together.

[0006] In accordance with another aspect of the invention, there are provided medical stimulation systems and methods incorporating a high energy density source, e.g., a zinc-air battery having increased airflow. Therefore, advantageously, due to the small prismatic shape and small size of the power source, such systems can be housed in a much more compact and useful space than has heretofore been possible. Moreover, due to the cost of the power source, it represents an inexpensive, i.e., a $1.00 per day, throw-away primary battery that may be used in systems directed toward helping people hear again, walk again, and regain body functionality which they may have otherwise lost permanently.

[0007] One embodiment of the invention may be characterized as a small high energy density battery having a rectangular solid shape with dimensions of approximately 8 mm thick by 20 mm long by 17 mm wide. Such a small prismatic shape allows it to fit slidingly into a behind-the-ear external speech-processing component of a cochlear implant system. Hence, while existing cochlear implants systems use belt-mounted batteries and speech processors, the system of the present invention with its new high-density energy source allows the belt-mounted batteries and speech processor to be dispensed with and to be replaced by a lightweight behind-the-ear (BTE) unit.

[0008] The casing of the high energy density source includes a non-reactive plastic or other non-reactive material, which contains small holes in it. Or it is in part, or, whole, permeable to air allowing a sufficient flow of air to enter so that the air may react with the zinc in the zinc-air battery configuration to produce the desired power. A characteristic feature of a zinc-air battery is that the energy produced by the battery results from a reaction between the oxygen in the air and zinc. Moreover the amount of energy produced is, in large part, a function of how much air is flowing to the air electrode part of the battery.

[0009] Smaller “button” batteries of the zinc-air type disadvantageously have high series equivalent impedance. In order to get a higher current and power and lower impedance from this battery type, a larger size is needed. Prior teaching is toward a small size because the amount of air required for a smaller battery is more easily accomplished, while the casing of a larger battery makes it impossible to supply the required air. The present invention advantageously overcomes these difficulties and provides a lower impedance battery in a small prismatic package having higher energy density than has been heretofore achieved.

[0010] Thus, with the invention herein, a whole new area is opened up for neuromuscular electric stimulation, as well as for cochlear implants, requiring a small, high energy-density source.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The above and other features and advantages of the invention will be more apparent from the following detailed description wherein:

[0012]FIG. 1a is a high energy density primary zinc-air battery with permeable casing;

[0013]FIG. 1b shows a Behind-The-Ear (BTE) cochlear implant component with battery receiving chamber;

[0014]FIG. 1c shows a different embodiment of is a high energy density primary zinc-air battery with permeable casing;

[0015]FIG. 1d shows another embodiment of the BTE cochlear implant component with a variant battery holding unit;

[0016]FIG. 1e shows a different embodiment of is a high energy density primary zinc-air battery with permeable casing;

[0017]FIG. 1f shows another embodiment of the BTE cochlear implant component with a different variant battery holding unit;

[0018]FIG. 2a shows a permeable casing that utilizes small holes;

[0019]FIG. 2b shows a permeable casing made from a permeable material which covers the holes;

[0020]FIG. 2c shows a permeable casing having internal air-ducts with small holes;

[0021]FIG. 2d shows another type of permeable casing utilizing internal air-ducts with permeable material;

[0022]FIG. 3a shows the range of dimensions of a zinc-air battery for use in cochlear implant systems;

[0023]FIG. 3b similarly shows an additional range of dimensions of a zinc-air battery for use in cochlear implant systems;

[0024]FIG. 4 depicts several lightweight, high energy density disposable primary battery systems for powering neural stimulators, muscle stimulators, neuromuscular stimulators and living tissue stimulators;

[0025]FIG. 5a illustrates details of a cochlear implant system BTE unit battery holder, showing standoffs that aid in the air circulation to the battery and its permeable case;

[0026]FIG. 5b similarly shows the details of a cochlear implant system BTE unit battery holder, with keyed standoffs that aid in the air circulation to the battery; and

[0027]FIG. 5c depicts details of a permeable surface battery holder for use with the cochlear implant system BTE unit that aids in the air circulation to the battery.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is merely made for the purpose of describing the general principles of the invention. The scope of the invention should be determined with reference to the claims.

[0029] As in FIG. 1a, the zinc-air battery (11) may be slid into a battery receptacle (13), for example, as in FIG. 1b, of a behind-the-air unit of a cochlear implant system (12). As shown in FIG. 1c, in another embodiment, the zinc-air battery (111) slides into the battery holder of the BTE (112) part of the cochlear implant system, as in FIG. 1d. The electrical contacts (113) of the BTE (112) unit mate by simple spring pressure to the corresponding contact points on the zinc-air battery (111), which are not shown. A third embodiment is shown in FIG. 1e, with the zinc-air battery (1111) slidingly mating with the BTE battery holding case (1114) as shown in FIG. 1f. The battery case (1114) has large air openings (1112) as well as spring loaded electrical contacts (113) which contact corresponding electrical contacts on the battery (1111)

[0030] The zinc-air battery uses the oxygen from the air as one electrode and a consumable metal, zinc, as the other electrode. The electrochemical reaction is mediated by a suitable electrolyte. A principal advantage of the zinc-air battery is that the weight and volume of the battery are cut way down, because one electrode is consumable, ambient air, and an amount of a second metal corresponding to that of the first electrode need not be included. However, to get the air to the electrochemical reaction, provision for the air to come into the battery, e.g., holes, permeable membranes, and airways or such, need to be provided.

[0031] In the range of air-zinc battery weight, size, and power considered for the present invention, more provision for air entry is required than in a simple button battery. That is, a simple hole will not suffice to provide the necessary air transport. On the other hand, an air management system with fans, and possibly coolers and heaters and active desiccator(s) and/or humidifier(s), would be prohibitive in expense, size, and weight for the batteries in the present invention, but would be suitable for the case of some larger zinc-air batteries.

[0032] An embodiment shown in FIG. 2a uses small holes (21) in a rigid case (22) to enable and facilitate the diffusive transport of air to the zinc-air battery unit in sufficient quantity. The sufficient quantity is such that a zinc-air battery of the sizes (31), (32), shown in FIGS. 3a and 3 b, operates in the required power flow range. The quantitative sizes are discussed in the third paragraph below, in conjunction with FIG. 3a and FIG. 3b.

[0033] Another embodiment (FIG. 2b) uses a permeable membrane (23) supported by a rigid frame or case with a case with areas cut out (24). Another embodiment (FIG. 2c) shows small pipes (25) connected through the case (26) to the outside air. These small pipes (25) have small holes (27) where the pipes are internal to the battery in order to enable the air to diffuse to more places internal to the battery case (26). Another embodiment (FIG. 2d) uses permeable membrane(s) (28) over open areas in the small pipes (25) to enable the air transport.

[0034] In all embodiments of this invention, care is taken to prevent the electrolyte, typically corrosive, such as ammonium chloride, potassium hydroxide, or neutral manganese chloride, from leaking out. Any leakage of the corrosive electrolyte could potentially harm the patient. Therefore, typically, many small, laser-drilled holes are used, which acting together with the surface tension of the electrolyte and a hydrophobic coating material such as carbon black is used to prevent electrolyte escape. Another embodiment utilizes a membrane such as tetrafluoroethylene (DuPont TEFLON) to allow the entry of air, but prevent the escape of the electrolyte.

[0035] One embodiment (FIG. 3b) of the invention is a rectangular solid shape with dimensions 6 mm (±20%) thick (36) by 25 mm (±20%) long (37) by 17 mm (±20%) wide (38), such that it can fit slidingly into a behind-the-ear (BTE) external speech-processing component of a cochlear implant. An example of an implantable cochlear stimulator is described in U.S. Pat. No. 5,603,726, which is hereby incorporated by reference. An example of a type of BTE is described in U.S. Pat. No. 5,824,022 (to issue Oct. 20, 1998), that is hereby incorporated by reference. The positive (39) and negative (399) terminals are shown. Another embodiment (FIG. 3a) of the invention is a rectangular solid shape with dimensions 6 mm (±20%) (31) thick by 20 mm (±20%) long (32) by 10 mm (±20%) wide (33). The positive (34) and negative (35) terminals are shown. Many cochlear implants use belt-mounted batteries and speech processors. The new high-density energy source allows these latter to be dispensed with and replaced by a lightweight behind-the-ear (BTE) unit.

[0036]FIG. 5a shows details of how the battery and its case are situated in the BTE cochlear implant system battery receptacle. The BTE battery holder (51) uses stand-offs (52) to allow the zinc-air battery (53) to be surrounded by air spaces (54). These air spaces allow the permeable surface (55) of the zinc-air battery (53) to have a sufficient air supply. A similar case is shown in FIG. 5b, except that here one or more standoffs (56) are keyed so as to place the positive and negative terminals of the zinc-air battery (53) correctly. FIG. 5c shows another embodiment of the BTE battery receiving housing (51) for providing air access to the zinc-air battery (53). Different surface structures such as (57) with perforations on the inner and outer layer of the BTE battery receiving housing, with a baffle unit (578), structure (58) with perforation (577) and baffle unit (578), structure (59) with perforation (577), and structure (599) with perforation (577) and permeable membrane (5999).

[0037] The zinc-air batteries typically have, in the uses cited, a flat electrode geometry. In that case the air holes and air tube ducts are arranged so as to lead oxygen (in the air) to the air electrode and to return the air which is slightly depleted in oxygen after reacting with the zinc via the battery electrolyte. In another embodiment, the electrode pairs may be cylindrical or piecewise planar. In these cases, the air holes and/or ducts are arranged to maximize the transport of air to and from the air electrode.

[0038] A further embodiment utilizes the small tubes and tubules as mechanical elements to help prevent the desiccation in a dry ambient condition (approximately, below 40% relative humidity).

[0039] Similarly the same mechanical structure is used to help prevent “flooding” of the electrolyte, too much water in the electrolyte when the ambient conditions have high humidity (approximately, above 60% relative humidity).

[0040] The permeable membrane embodiments also may act to prevent desiccation and flooding, as well as to prevent carbon dioxide and other contaminants, such as tobacco smoke from entering the battery and decreasing its efficiency.

[0041] The invention is a method as well as an apparatus for increasing the air flow to a Zinc-air battery such that the energy density, approximately, is from 500 mwh/cc to 1000 mwh/cc allowing about 8 to 16 hours use as a primary (throw-away) battery. It is designed for and is particularly good for use with, for example, high-duty cycle, high-drain cochlear implants, and neuromuscular stimulators for nerves, muscles, and both nerves and muscles together. FIG. 4 shows various uses of the present invention. Zinc-air battery (ies) (41) may enable limb movement and locomotion via neuromuscular stimulators (42), spinal column stimulators (43), and may allow more effective use of the BTE component of cochlear implant systems (44).

[0042] The systems incorporating the high energy density energy source are also part of the invention, as well as the resulting apparatus of the method. The uses of this inexpensive, (i.e., approximately a cost of one dollar per day), throw-away primary battery are new uses of the modified zinc-air battery and are directed toward helping people hear again, walk again, and regain body functionality which they have otherwise lost permanently.

[0043] It is noted that while zinc-air batteries may be obtained commercially from numerous sources, e.g., Electric Fuel, Ltd., Har Hotzvina Science Park, P.O.B. 23073, Jerusalem, 91230, Israel, the present invention is not directed to zinc-air batteries per se. Rather, the invention is directed to zinc-air systems that include a zinc-air battery in a small, prismatic shaped case that allows sufficient air to enter the battery case so that a high power output is achieved, at low cost.

[0044] While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims. 

What is claimed is:
 1. A zinc-air battery system comprising a zinc-air battery with a porous cover.
 2. The system of claim 1 wherein the porous cover further comprises small holes.
 3. The system of claim 1 wherein the porous cover further comprises permeable membranes.
 4. The system of claim 1 wherein the porous cover further comprises a network of small pipes connected through the outside cover wherein said pipes are perforated along their lengths by small holes.
 5. The system of claim 1 wherein the porous cover further comprises a network of small pipes connected through the outside cover wherein said pipes are perforated along their lengths by openings that are covered by permeable membrane(s).
 6. The system of claim 1 further comprising a behind-the-ear cochlear implant component wherein the existing, already-implanted cochlear implant component requires a power flow from outside the body of 200 mW to 10,000 mW.
 7. The system of claim 6 wherein the dimensions of the zinc-air battery system are from 16 to 30 mm in height, 8 to 20.4 mm in width, and 4.8 to 7.2 mm in depth.
 8. The system of claim 7 wherein for a depth in said range, the width and height dimensions may range above and below said maximum values further comprising dimensions which maintain the battery output of at least 500 mWh per cc, further comprising dimensions which do not require a rectangular profile in the height-width plane.
 9. A method for enabling and enhancing airflow into a zinc-air battery system comprising the step of fitting said zinc-air battery with a porous cover.
 10. The method of claim 9 comprising the step of creating the porous cover by perforating or etching it with small holes.
 11. The method of claim 9 comprising the steps of creating the porous cover by making openings in the cover and covering the openings with permeable membrane.
 12. The method of claim 9 comprising the steps of creating the porous cover by connecting a network of small pipes through the outside cover and perforating said pipes along their lengths by small holes.
 13. The method of claim 9 comprising the steps of creating the porous cover by connecting a network of small pipes through the outside cover and making openings in said pipes along their lengths and covering said openings with permeable membrane(s).
 14. The method of claim 9 comprising the step of using a zinc-air battery with enhanced air flow to power a behind-the-ear cochlear implant external component wherein the existing, already-implanted cochlear implant component requires an energy flow from outside the body of 200 mWh to 10,000 mWh.
 15. The method of claim 14 comprising the steps of fabrication the zinc-air battery with dimensions from 16 to 30 mm in height, 8 to 20.4 mm in width, and 4.8 to 7.2 mm in depth.
 16. The method of claim 15 comprising, fabricating said battery, with a depth in said range, and width and height dimensions ranging above and below said maximum values and making the dimensions so that the battery output is of at least 500 mWh/cc and making the dimensions so as not to require a rectangular profile in the height-width plane.
 17. The method of claim 9 further comprising using said porous-covered battery as an inexpensive, through-away, high energy density source for existing cochlear implants requiring said high energy density source and using said porous-covered battery for nerve, muscle, neuromuscular, and living tissue stimulators, and functional electric stimulators, and enabling damaged or severed nerve persons, to walk, move limbs, again, in the case of such lost functionality. 